My, what new teeth you have!

Life reconstruction of Tiarajudens eccentricus, displaying saber-teeth to prevent approach of a carnivorous dinocephalian.
[Illustration by Juan Cisneros]

Chewing an apple—or if you're unlucky, a Brussels sprout –is trickier than it looks. To crunch up a tough fruit or vegetable like that, your top teeth and your bottom teeth need to fit together when you bite down. Scientists have now discovered a 260 million-year old fossil that may have been one of the first of its kind to have this type of special bite.

The fossil, parts of a smashed-up skull and some teeth, was found in Brazil by Juan Carlos Cisneros and his fellow researchers. They called their fossil Tiarajudens eccentricus. They think Tiarajudens is part of a group of ancient animals called therapsids, some of whom are relatives of today's mammals.

Eccentricus means "weird." And yes, this fossil is a little weird. It was probably about the size of a large dog, and its top and bottom teeth do fit together. But the roof of Tiarajudens' mouth looks like it was covered in teeth, from back to front. It's also got a pair of saber teeth, each one as long as a crayon.

Tiarajudens was a plant-eater, so that nicely-fit bite probably helped it chew up all kinds of tough, high-fiber plants. But aren't saber teeth kind of a meat-eater thing? Cisneros and the other scientists say their fossil may have used its dagger teeth to scare off predators—or each other.